The singer's team tweeted about her egg getup, which also prompted Twitter reaction from celebrities including Kelly Osbourne, Rose McGowan and Piers Morgan.

The singer, who wore a meat dress to September's Video Music Awards, showed up on the red carpet in downtown Los Angeles encased in a giant egg carried by four half-naked attendees -- including model Anne Vyalitsyna, girlfriend of Maroon 5 frontman Adam Levine (she appeared in the band's video for "Misery").

Before her arrival on the red carpet, Gaga's Twitter followers got this message: "This is Nicola, Haus of Gaga: Gaga is in incubation. Tonight's performance is in collaboration with Hussein Chalayan and House of Mugler. X"

Gaga's longtime producer RedOne says he knew about the stunt for two months.

"No idea of Gaga's would surprise me," he told The Hollywood Reporter on Sunday at the show.

Upon her arrival, celebrities and others took to Twitter to comment on the "outfit."

"@ladygaga incubating in her egg!!!" tweeted Rose McGowan.

Kelly Osbourne tweeted a photo of the singer in her getup.

"You will not believe your eyes when you see how @ladygaga showed up to the Grammys," the reality star wrote.

Even the Grammy organization chimed in about the star's via Twitter, saying "Lady Gaga just arrived in an egg!" That message was retweeted by several others.

Meanwhile, Piers Morgan saw it as an opportunity to make a quip -- and promote his own CNN show: "Think I might host tomorrow's @PiersTonight in same outfit that @ladygaga wore to #Grammys."

Morgan and other also were labeling their Gaga-related tweets with the tag "#eggstraordinary."

Still, not everyone was excited about the stunt. Some red-carpet photographers were miffed as to why they had to shoot an egg with a faint shadow of Gaga inside.

Said one red carpet shutterbug: "It's like a theater of the absurd. Everyone was just waiitng for the egg to hatch. We were all screaming open it up! She pushed her face against it but you could barely see her."

Word is that the singer will return to the carpet and actually exit the egg at some point.